Why not both? Windmills are intermittent, hugely dependent on location, short lifespan, requires a lot of space, dangerous to service etc etc. It's not a full solution.
Jeder Euro fürs Atom fehlt uns beim echten Ökostrom.
Because if you habe finite resources, you better invest them in something that works than waste a considerable part to do something that probably maybe should work.
Money is a 'finite' resource in the sense that we have largely agreed that it is finite. Funnily enough, we only manage to agree that it's finite for some things (education, health care, climate change) but not others (police, militaries, extravagant government buildings).
In terms of actual physical and labour resources, they're not fungible. People working on nuclear power or geothermal are not going to be terribly useful to advance the state of the art on wind power, which is already a largely mature technology that needs money and effort put into deployment not research. They also use largely different materials, technology, and equipment.
Likewise, you can't just take "money spent on geothermal" and throw it at "building windmills" because there are other bottlenecks involved in windmills that aren't just magically solved with money. And, of course, likewise.
Anyways, every advance in materials science all of these things engage in helps all of them advance.
